German patent documents nos. 197 01 055 and 199 57 556 refer to and discuss micromechanical semiconductor pressure sensors which have a frame made from a semiconductor substrate and a diaphragm disposed on the frame. In this context, mounted on the diaphragm are various piezoresistive measuring resistors which change their resistance value in response to a deformation of the diaphragm or of the resistors (as a result of a differential pressure between the upper side and the lower side of the diaphragm). The frame and the diaphragm are formed, in this context, from a silicon substrate by masking and subsequent etching of the back side. A potassium hydroxide etching solution (KOH etching solution) may be used for producing a cavity having a truncated pyramid shape tapering in the direction of the lower side of the diaphragm and having a trapezoidal cross-section.
German patent document no. 41 30 044 refers to and discusses a semiconductor pressure sensor which includes a silicon substrate having a diaphragm on a base made of borosilicate glass. In this context, the diaphragm is etched anisotropically from the silicon substrate, using a KOH-water solution or the like, a depression having typical angle measurements being created. The base, as against this, has a central hole for pressure application, via which the diaphragm is able to communicate with the outside.